1. Field of the Invention
The present invention relates to a reception method and a reception apparatus suitable for application to reception of a multicarrier signal in the form of burst data, for example, and a timing detecting apparatus applied to the above reception.
2. Description of the Related Art
Various radio telephone systems have been put into practice. Communication systems which have been applied to a radio telephone system are basically the same as a communication system for communicating between fixed stations.
A reception signal received by a portable communication terminal such as an automobile telephone, a portable telephone or the like is easily distorted because of multipath fading. Specifically, the multipath fading largely delays transmission of a signal among respective paths, and intersymbol interference is caused to thereby overlap codes located adjacent to each other. Therefore, a transmission characteristic is degraded.
In order to satisfactorily receive a signal even in case of such degradation of the transmission characteristic, it is necessary to employ a synchronous detecting circuit having a complicated arrangement formed of an adaptive equalizer and a phase-locked loop (PLL) circuit, which complicates an arrangement of a receiver and increases manufacturing costs thereof.
In order to solve the above problem, the assignee of the present invention has proposed a communication system for transmitting information by using phase difference between respective carriers in a so-called multicarrier system in which a plurality of carriers are simultaneously transmitted (in Japanese patent application No. 216311/1996 and so on).
In a communication system employing such multicarrier system, it is difficult to carry out a precise timing processing. Specifically, it is difficult to precisely synchronize a timing used for demodulating a reception carrier at every one modulation unit time of a transmitted signal, and hence the demodulation timing tends to be offset. If the demodulation timing is offset, an error depending upon a carrier frequency occurs in a demodulated phase information, which increases a determination error rate. If the synchronization data is added to the transmission data in order to keep the demodulation timing, then an amount of information which can be transmitted is reduced to that extent, which lowers a transmission efficiency.